Citadel DLC Walkthrough Part 2

Back at Anderson's Apartment Shepard and company get properly acquainted with Brooks, and the rest of the crew arrives.

Take some time to speak to each of the crew members then speak to Liara who says she has some info and wants to get everyone together to talk about it (she'll also offer the option to wait until later). Liara will explain that she's uncovered a casino owner that seems to be connected to the identity theft in some way. The goal is now to attend a black tie benefit at the casino, and have Brooks infiltrate the panic room where Khan is likely to be, while Shepard and his squad mates run interference for her on the casino floor.

Select a squad mate to join Shepard and Brooks at the Casino, but don't think too hard about the choice - there won't be any combat involved in this part of the mission.

Go up the stairs into the Casino and use the mingle option to interact with various patrons and employees. After a minute or so, Shepard will hear Brooks' voice asking him to meet her upstairs by the shaft. Find the stairs, head up, and take a left at the dance floor to find Brooks.

Brooks will give Shepard special lenses that allow him to see security wiring, and a box will pop up on the screen to alert the player of the current security threat. If the security threat status goes to "suspected", have Shepard find someone to mingle with as soon as possible to remove the threat.

To get the vent open for Brooks, Shepard needs to follow the wiring to the junction box past the other side of the dance floor. Before messing with the junction box he'll need to disable the security camera on the wall to the right of the junction box. Once the camera is disabled, Shepard only has a few seconds to bypass the junction box before the camera comes back on.

Spend some more time mingling and/or hitting the dance floor while Brooks begins to make her way through the vent. After a couple more minutes Brooks will alert Shepard that there is a guard directly below her. Head back downstairs and find a guard leaning against a partition wall. Have Shepard speak to him and narc out a supposed drug user in the bathroom, distracting the guard and clearing the way for Brooks.

Time for mingling while Shepard waits for Brooks' next communique. After a few minutes Brooks will tell Shepard the he needs to disable two sensors. Follow the red wiring on the floor to a sensor power box on a wall near the roulette tables. Before disabling the power box, Shepard needs to identify a nearby guard, and send his squad mate to distract him. Just look at the guard to select him, and use the same command Shepard uses in battle to order squad mates around. Once the guard is being distracted, Shepard has a short period of time to disable the sensor box (make sure the security threat is clear before starting).

With the first box disabled, follow the red wiring across the Casino to another box in a different gaming area. Use the same technique to distract the guard, but this box also has a security camera next to it which will need to be disabled before the box can be bypassed. Move quickly and remember if Shepard becomes suspected, just find someone to mingle with.

Once both boxes are disabled, a brief cut scene launches in which Brooks tells Shepard she's gotten herself in trouble and another guard will need to be distracted. Find the marked guard (back over by the roulette area) and distract him.

After a few more minutes of mingling Brooks will ask for Shepard's help with a security gate. Follow yellow wiring into a small side room with a couple of cameras and a guard. Send the squad mate to distract the guard, and disable the camera by the couch first, then quickly disable the other camera, before the first camera comes back online and while the guard is still distracted. With both cameras disabled quickly move to the right to find the sensor power box and disable it. Once it's successfully disabled, a cut scene will launch and this part of the mission will finish, returning the trio to Anderson's Apartment to try and gather information from Khan's drives and prepare for the next part of the mission.

With this portion of the mission completed, the High Society achievement / trophy will unlock, and credits, paragon/renegade points, and reputation points will be awarded.